1. Field of the Invention
This invention relates to packer systems for use in oil and gas wells, and more particularly, to a packer system adapted to be run into a well bore and installed inside a polished bore receptacle (PBR) to isolate an existing but malfunctioning PBR system.
2. Description of Related Art
Downhole packer systems have previously been disclosed, for example, in U.S. Pat. Nos. 4,288,082, 4,457,369, 4,898,245 and 4,972,908. Packer systems are typically used for blocking fluid flow through an annulus defined by production tubing disposed within a casing string. Because formation fluids can be highly corrosive and/or hot, tubing strings are frequently used to protect the casing from formation fluids as they flow from a producing zone to the well surface.
U.S. Pat. No. 4,288,082 discloses a well sealing system designed to be run on a tubing string in a casing system having restrictions that are adapted to engage and support the guide sleeve and protective cylinder of the packer assembly. The packer is set by the weight of the tubing string acting on slips disposed above elastomeric packing elements, causing the slips to engage the interior wall of the casing.
U.S. Pat. No. 4,457,369 discloses a retrievable well packer designed for use at high temperatures and pressures that is explosively set by a running tool and then connected to a tubing string. The well packer has a tubular mandrel; upper and lower slips in spaced relation on the mandrel, each comprising a one piece, C-shaped member; means on the mandrel for expanding each of the slips; means for locking the upper slips in expanded condition; and an expandable seal assembly disposed on the mandrel between the slips. The slip assemblies are arranged so that the lower slip assembly sets first and the upper slip assembly last, while the upper slip assembly releases first and the lower slip assembly releases last when pulling the packer.
U.S. Pat. No. 4,972,908 discloses a packer arrangement wherein the operating string is released from the tubular member on which the packer is supported before the packer can be expanded into sealing position. Means for locking tubular members against relative longitudinal movement are disclosed to prevent premature expansion of the packer into sealing position. Actuation can be accomplished by hydraulic action alone, mechanical action alone, or a combination of mechanical and hydraulic action.
U.S. Pat. No. 4,898,245 discloses a packer arrangement that can be used as a permanent production packer or as a retrievable packer in well bore tubulars. The packer can be hydraulically, mechanically or explosively set, and can be retrieved by wireline or coiled tubing. Use of the packer arrangement in a casing having a liner with a packer bore receptacle is also disclosed, with the packer arrangement being connected to a landing nipple secured inside the liner.
A packer system is needed, however that can be installed in a casing and polished bore receptacle assembly to isolate an existing but malfunctioning packer system without the need for a landing nipple as required by the invention disclosed in U.S. Pat. No. 4,898,245.